| Influence from roof platform and piping is always a problem for the design of cryogenic storage tank. The uncertaining of platform and piping load distribution on roof was followed by uncertaining of tank local stress. General design method by estimated uniform load substitute of roof platform and piping load should lead to disreliable design.this paper focused on a certain30000m3single containment cryogenic storge outer tank, analysied the stress status of outer tank under installation load, operation load, wind load and test load, and also checked the stability of the tank under vacuum load by linar and non-linar buckling analysis.For the static analysis of outer tank, the modal of outer tank was built by shell93and beam189elements.applied gravity, platform load, live load, wind load, vacuum, design pressure and test pressure according to different load cases. Applied fix point at the bottom of the tank.analysis showed local axial compression area stress of some exceded allowable stess, where at the topest lay of wall and just under the platform.After increased the thickness and have a detail stress check on bi-axial stress of shell,circumstance stess of compression ring and roof stress intensity. The analysis confirmed the validity of the initial design except for the area of topest shell under the roof platform.For the linar buckling analysis of tank, by many times linar buckling analysis and manually amplifying the live load, worked out the live load safety factor and first round buckling modal when the buckling factor is1. These results will be the base of non-linar backling analysis.For the non-linar buckling analysis, base the flaw distribution on first round buckling modal, creating the maximum initial flaw according the construction roundness telorance, excuted a non-linar buckling analysis of the tank, verified the vacuum buckling factor of tank shell and roof, compared with the result of linar buckling analysis and linar static analysis. |
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